Chair For Extended Seating Periods

ABSTRACT

In order to provide comfort during prolonged seating periods and facilitate proper sitting posture, a chair is configured to include a central chair portion defining a pair of seat back mounting sections, a pair of front leg mounting sections, a pair of rear leg mounting sections, and a seat surface. A seat back including a pair of seat back extensions is provided, with each of the seat back extensions mountable on one of the seat back mounting sections. A pair of front leg extensions is mountable on the front leg mounting sections of the central chair portion, while a pair of rear leg extensions is mountable on the rear leg mounting sections of the central chair portion. Such a chair construction permits the seat back, the front leg extensions, and the rear leg extensions all to be adjustable relative to the seat surface and lockable in any of a plurality of discrete positions with respect to the seat surface.

The present application is a continuation application of application Ser. No. 11/689,861 filed Mar. 22, 2007, which claims the priorities of U.S. Provisional application Ser. No. 60/786,049, filed Mar. 27, 2006, and U.S. Provisional application Ser. No. 60/872,591, filed Dec. 4, 2006, the disclosures of which are incorporated herein by reference in their entireties.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to the configuration of a chair, occasionally referred to as an ALCAT chair in the following description, that facilitates good, relaxed posture and, at the same time, provides adequate total back support when a user is properly seated, as well as certain methods of using such a chair to provide greater comfort during prolonged sitting sessions. The invention is ideal for musicians or other individuals who find it necessary or desirable to remain seated for extended time periods.

2. Description of Related Art

Chairs in common use today have a number of basic problems. Typically such a chair includes a solid, full back rest defining, together with a seat surface, a minimal opening at the base of the back rest. Various attempts have been made to improve chair comfort, such as the provision of ergonomic curves providing lumbar and overall back support and curved or scooped out seat surfaces. The user of a chair having such features, however, still typically must exert significant physical effort to sit with good, relaxed, comfortable posture, which is essential if that user is to remain seated for an extended time period. A conventional chair construction tends to force a user to sit on gluteal muscles, impose a backward curve to the spine, and produce a caved-in chest, affecting heart and lung efficiency. Shoulder tension may also affect the arms and hands of a user while seated on a conventionally configured chair, and a rounded lumbar and/or sacral area tends to produces muscle stress and potentially creates possible danger to vertebrae due to possible herniation or exacerbation of other existing conditions.

A conventional chair construction is shown in FIG. 16. When viewed laterally, with “good” sitting posture, a plumb line P perpendicular to the floor F should be aligned with the user's ear, shoulder, hip joint, and ischium, and a line L parallel to the floor at the level of the user's hip joint is preferably slightly higher than the user's knee joint. The user of a conventional chair construction such as that shown in FIG. 16 could have significant difficulty is achieving or maintaining this “good” sitting posture, i.e. a posture considered to provide the most relaxed sitting position, in which the pull of gravity on the user's body and associated stresses produced due to misalignment are minimized. As it is difficult for the user to keep his or her torso in an essentially upright or perpendicular position relative to the seat surface, a relatively large body area is subjected to the force of gravity. If a chair such as that shown in FIG. 16 has a scooped or rounded seat surface and a minimally open space between the backrest and the seat surface, such problems could be amplified.

SUMMARY OF THE INVENTION

It is one object of the invention to provide a chair configuration that both facilitates good, relaxed posture and provides adequate total back support when a user is properly seated.

Another object of the invention is to use such a chair configuration to produce greater comfort during prolonged sitting sessions, thus rendering it ideal for musicians or other individuals who find it necessary or desirable to remain seated for extended time periods

These objects, as well as other objects and various features and advantages that will become apparent, are achieved by way of a chair according to the invention that is particularly adapted to provide comfort during prolonged seating periods and to facilitate proper sitting posture. Such a chair, according to the invention, includes a central chair portion defining a pair of seat back mounting sections, a pair of front leg mounting sections, a pair of rear leg mounting sections, and a seat surface. A seat back including a pair of seat back extensions is provided, with each of the seat back extensions mountable on one of the seat back mounting sections. A pair of front leg extensions are mountable on the front leg mounting sections of the central chair portion, while a pair of rear leg extensions are mountable on the rear leg mounting sections of the central chair portion. The seat back, the front leg extensions, and the rear leg extensions are all adjustable relative to the seat surface and lockable in any of a plurality of discrete positions with respect to the seat surface to produce the improved comfort during prolonged sitting sessions as noted above.

The central chair portion may be either collapsible or substantially rigid and non-collapsible. Manually releasable latches, biased into locking engagement, may be disposed on the central chair portion to releasably secure the seat back, the front leg extensions, and the rear leg extensions in position relative to the seat surface. The front leg extensions, the rear leg extensions, or both the front leg extensions and the rear leg extensions can be substantially rigidly connected to each other by a support strut, if desired. It is also possible to include an arm rest assembly having an arm rest surface that is also lockable in a plurality of discreet positions relative to the seat surface. Rollers or casters could be disposed at ends of the front and rear leg extensions.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view from above of a first ALCAT chair embodiment.

FIG. 2 is an exploded posterior view showing a first support frame, an adjustable seat back, and adjustable leg extensions of the chair shown in FIG. 1.

FIG. 3 is an enlarged, part sectional view of a locking device formed by a manually releasable latch.

FIG. 4 is a front view of the elements illustrated in FIG. 2 in an assembled condition.

FIG. 5 is a top view of the seat or seat surface of the chair as well as of the supporting frame for the seat.

FIG. 6 is a side view of the seat shown in FIG. 5.

FIG. 7 is an enlarged view of one of a pair of hinge links partially interconnecting the support frames and seat of the first chair embodiment together.

FIG. 8 is a view illustrating a second support frame and adjustable leg extensions of the chair shown in FIG. 1.

FIG. 9 shows a second embodiment of a chair according to the invention that includes rollers or casters mounted on lower ends of the leg extensions.

FIGS. 10 and 11 show an adjustable arm rest assembly.

FIGS. 12 and 13 illustrate yet another embodiment of the chair in which the central portion of the chair is substantially rigid and non-collapsible.

FIG. 14 shows the user of a chair according to the invention in one preferred sitting position.

FIG. 15 shows the user of a chair according to the invention in another preferred sitting position.

Figure illustrates a user sitting on a conventionally constructed chair.

DETAILED DESCRIPTION OF THE INVENTION

The manner in which a first support frame 30, a second support frame 40, and a seat 50 cooperate to define a collapsible central portion of a first ALCAT chair embodiment is apparent from FIG. 1. The first support frame 30 is configured as a substantially rigid, approximately “H” shaped structure having substantially parallel side legs 32 interconnected by a laterally extending strut 34. The side legs 32 and the strut 34 could be made of any material appropriate for construction of collapsible chairs, such as wood, aluminum, steel, or plastic having sufficient strength and stiffness. In one configuration, the legs 32 and the strut 34 are constructed of ⅞″ steel tubing, with the strut 34 spot welded at its ends to the legs 32 at appropriate locations 36.

The second support frame 40 is also configured as a substantially rigid, approximately “H” shaped structure. The second support frame has substantially parallel side legs 42 interconnected by a laterally extending strut 44. Again, the side legs 42 and the strut 44 could be made of any material appropriate for construction of collapsible chairs. In one configuration, the legs 42 are constructed of ⅞″ steel tubing and the strut 44 is constructed of ⅝″ steel tubing, with the strut 44 spot welded at its ends to the legs 42 at appropriate locations 46 (indicated in FIG. 8).

The seat 50 is defined by a substantially rigid seat frame 52. As illustrated in FIGS. 1, 5, and 6, the frame 52 has a square or rectangular perimeter, but it is to be noted that the perimeter of the frame 52 could be circular or oval or could have any other appropriate configuration. The seat surface 54 could either be constructed integrally together with the frame 52 as a single piece of material or, as shown in FIG. 1, defined by a separate, possibly removable, upholstered cushion or fabric surface, configured as desired aesthetically. It is imperative, however, that the seat be relatively flat and firm.

A pair of hinge links 60 cooperates with the seat frame 52 to interconnect the first support frame 30, the second support frame 40, and the seat frame 52 together to produce the collapsible central ALCAT chair portion. Holes 64, best shown in FIG. 7, are drilled or otherwise defined at forward and rearward ends of the hinge links 60. The side legs 32 of the first support frame 30 are provided with holes 38 adapted to align with respective holes 64 at forward ends of the hinge links 60, while the legs 42 of the second support frame have holes 48 adapted to align with respective holes 64 at rearward hinge link ends. Bolts, rivets, or other such elements 62 extend through each aligned pair of holes 38, 64 and 48, 64 to pivotally secure each of the side legs 32 and 42 to respective ends of the hinge links 60.

Each of the first support frame side legs 32 is also provided with a hole 39 provided at a location below the location of the hole 38, while each of the second support frame legs 42 is also provided with a hole 49 provided at a location below the location of the hole 48. A bolt, rivet, or other such element 66 extends through each of the holes 39 in the first support frame 30 and an aligned hole 53 in the seat frame 52 to pivotally secure each of the side legs 32 to the seat frame 52. Another bolt, rivet, or other such element 66 also extends through each of the holes 49 in the second support frame 40 and an aligned hole 55 in the seat frame 52 to pivotally secure each of the side legs 42 to the seat frame. Connecting a first support frame leg 32, a second support frame leg 42, one of the hinge links 60, and a side of the seat frame 52 together in this way produces a roughly trapezoidal lateral link 70 as shown in FIG. 1. Upper ends of the second support frame side legs 42 may be provided with resilient rubber or plastic caps or bumpers 43. Abutment between outside surfaces of the side legs 32 and either the upper ends of the second support frame side legs 42 or the bumpers 43, if they are provided, serves, together with the lateral links 70, to stabilize the central ALCAT chair portion when the overall chair is in its expanded, in-use, open position.

A seat back 72 is mountable on the side legs 32 of the first support frame so as to be displaceable along the side leg longitudinal axes. In the configuration shown in FIGS. 1 and 2, the seat back 72 includes an approximately “U” shaped seat back frame 74 having a web 76 (FIG. 2) interconnecting the base 78 and legs 80 of the frame 74. For reasons that will become clear, the legs 80 can properly be referred to as seat back extensions. In one configuration, the base and legs could be formed of a unitary bent piece of 1″ steel tubing and the web could be a steel sheet of appropriate thickness welded to the tubing. For comfort and pleasing aesthetics, fabric or a separate, possibly removable cushion 82 could be constructed integrally with or attached removably to the seat back 72. As illustrated in FIGS. 1 and 2, the cushion 82 is attached removably to the web 76 by fasteners 84, such as screws.

To provide for locking the seat back 72 in a plurality of discrete positions along the side leg longitudinal axes, each leg 80 of the seat back frame 74 is provided with a longitudinally extending series of openings 86. In the configuration shown, the openings 86 are provided in walls of tubing forming the seat back frame 74. Each of the openings 86 is configured to cooperate with a spring button mechanism 90, which is provided near an upper end 100 of each first support frame leg 32 and defines a manually releasable latch. The spring button mechanism, best shown in FIG. 3, serves to lock the seat back frame legs 80 and the first support frame side legs 32 in position relative to each other. Each spring button mechanism includes an approximately cylindrical button or cap 92 welded or otherwise secured to or provided with a biasing element 94, such as a leaf or coil spring. In the configuration illustrated in FIG. 3, the biasing element 94 has a base 96 secured in any convenient manner to a wall of one of the first support frame legs 32. The button or cap 92 of each mechanism protrudes through an opening 98 in the support frame side leg 32 approximately diametrically opposed to the base 96.

To lock the seat back 72 in a discrete position relative to the first support frame side legs 32, the upper ends 100 of the first support frame side legs 32 are inserted into the larger diameter lower ends of the seat back frame legs 80. The tops of the legs 32 thus form a pair of seat back mounting sections. The buttons or caps 92 are biased under action of the biasing elements 94 through aligned openings 98 and 86 to produce releasable locking engagement between the seat back 72 and the first support frame 30. By pressing the buttons or caps 92 inwardly into openings 86 against forces applied by the elements 94, a user can disable locking engagement between the buttons or caps and the holes and adjust the overall position of the seat back 72 relative to the support frame 30. Once a desired relative position between the seat back 72 and the support frame 30 is reached, the buttons or caps 92 can be permitted by a user to remain engaged within the appropriate set of openings 86 to lock the seat back 72 in the desired position. Conventional locking nuts 102 may also be included at the lower ends of the seat back frame legs 80 to provide added or redundant frictional locking between the first support frame legs 32 and the seat back frame legs 80. The seat back 72 can be removed from engagement with the first support frame legs 32 by releasing the locking nuts 102, again pressing the buttons or caps 92 inwardly into openings 86 against forces applied by the elements 94 to disable locking engagement between the buttons or caps and the holes, and withdrawing the first support frame legs 32 from the lower ends of the seat back frame legs 80.

Each of the first support frame legs 32 also has a lower end 101 that is receivable in a respective leg or leg extension 104, which, as illustrated, is formed by a tube, constituting part of a first support leg extension frame 106. The lower ends of the legs 32 thus form a pair of front leg mounting sections for legs or leg extensions 104. The leg extension frame 106 includes a pair of the leg extensions 104 interconnected by a laterally extending support strut 108 and, as shown, is configured so as to have a substantially rigid, approximately “H” shaped structure. The leg extension frame 106 could be made of any material appropriate for construction of collapsible chairs, such as aluminum, steel, plastic having sufficient strength and stiffness, or even wood. As illustrated, the frame 106 is constructed of steel, with the support strut 108 spot welded at its ends to the leg extensions 104 at appropriate locations 110. Each of the leg extensions 104 is provided with a longitudinally extending series of openings 112 configured similarly to the openings 86 in the seat back frame. Each series of openings 112 respectively cooperates with another spring button mechanism 90, configured essentially the same as the spring button mechanism described above, located adjacent a lower end 101 of a support frame leg 32. The spring button mechanisms 90 and the openings 112 together provide for locking the first support leg extension frame 106 in and releasing the first support leg extension frame from discrete positions along the side leg longitudinal axes. Conventional locking nuts 102 may again be included around the upper ends of the leg extensions 104 to provide added or redundant frictional locking between the first support frame legs 32 and the leg extensions 104 of the first support leg extension frame 106. Rubber or plastic caps 114 can be provided at lower ends of the leg extensions 104 to avoid undue wear on floors or other support surfaces. FIG. 4 shows the first support frame 30, the seat back 72, and the first support leg extension frame 106 in an assembled condition.

Each of the second support frame side legs 42 has a lower end that is receivable in a respective leg or leg extension 120, which, as illustrated, is formed by a tube, constituting part of a second support leg extension frame 122. The lower ends of the legs 42 thus form a pair of rear leg mounting sections. The leg extension frame 122 includes a pair of the leg extensions 120 interconnected by a laterally extending support strut 124 and is configured essentially identically to the first support leg extension frame 106. Each of the leg extensions 120 is provided with a longitudinally extending series of openings 126, again configured similarly to the openings 86 in the seat back frame 74. Each series of openings 126 respectively cooperates with yet another spring button mechanism 90, configured essentially the same as the spring button mechanism described above, located adjacent the lower end of each of the second support frame side legs 42. FIG. 8 illustrates the buttons or caps 92 of such spring button mechanisms received in openings 126 to lock the second support leg extension frame 122 in a discrete position with respect to the second support frame 40. As with the first support leg extension frame 106, the spring button mechanisms and the openings 126 together provide for locking the second support leg extension frame 122 in and releasing that second support leg extension frame from discrete positions along the side leg longitudinal axes. Conventional locking nuts 102 may once again be included, this time at the upper ends of the leg extensions 120 to provide the added or redundant frictional locking noted previously, and rubber or plastic caps 114 can be provided at lower ends of the leg extensions 120.

Exemplary dimensions and compositions of certain parts of the ALCAT chair are mentioned above. Some of these dimensions and compositions will now be reiterated in the following overall discussion, which is set forth simply in order to provide an illustration of the size of one embodiment of the invention and is not to be considered limiting in any way. As noted above, the side legs 32 and the strut 34 can be formed of ⅞″ outer diameter spot welded steel tubing. Centers of holes 38 and 39 in each leg 32 can be separated by 2 inches, and centers of holes 38 can be separated from openings 98 by 9 inches. The center of each hole 39 can be separated from the longitudinal centerline of the strut 34 by 6″, and from the respective lower end 101 by 17″. The strut 34 may have a length of 16.25″.

Many dimensions of the frames 106 and 122 are essentially the same. The support struts 108, 124 may be formed of ⅞″ outer diameter tubing, can have a length of 16.125″, and may have centerlines displaced 3″ from the location of the locking nut 102 disposed at the upper end of leg extensions 104, 120. The leg extensions 104, 120 may be formed of 1″ tubing. Openings 86, 112, and 126 in each respective series of openings may be spaced 1″ apart, and each series shown in the drawing figures includes five openings.

The U-shaped seat back frame 74 may be constructed of 1″ outer diameter tubing, and the lateral fasteners 84 (FIG. 2) may be disposed approximately 10″ vertically from the underside of the locking nuts 102 disposed on ends of the legs 80.

The seat frame 52 may be 16″×16″, 0.125″ thick, and 1.50″-1.75″ deep. The hole 53 may have its center displaced 9″ from the front edge of the frame 52, while the hole 55 may have its center displaced 1.50″-1.75″ from the rear edge of the frame 52.

Finally, the hinge link 60 may be 4.5″ in length, the strut 49 may be 16.25″ in length, each hole 48 may be separated by 1.25″ from the tip of a cap or bumper 43 and by 5.5″ form a centerline of the strut 44. Each leg 42 may have an overall length of 19.75″.

The second ALCAT chair embodiment illustrated in FIG. 9 is essentially the same as the first embodiment, except that rollers or casters 130 are provided at lower ends of the leg extensions 104 in place of the caps 114 included in the first embodiment. The rollers or casters 130 provide the chair with improved mobility. The rollers may be approximately 2″ in diameter, although this dimension is not critical and could be significantly larger or smaller.

FIGS. 10 and 11 show a version of the second ALCAT chair embodiment having an adjustable arm rest assembly 132 mounted on one side 134 of the seat frame 52. The arm rest assembly 132, of course, could be utilized in conjunction with the first ALCAT chair embodiment described above. An additional adjustable arm rest assembly could also be mounted on the other side of the seat frame if support for both arms of the ALCAT chair user is desired.

The arm rest assembly includes a base 136 connectable to the seat frame 52, for example by fasteners, such as bolts, screws, or rivets, passing through holes 138. The base 136 may be a pressed metal sheet or solid metal, possibly plastic or another material, and includes an opening 139 in one of its walls through which a spring biased button 140 extends. The button 140 is dimensioned to protrude through any of a series of openings 142 provided in a stem 144 to which an arm rest 146 is mounted or with which the arm rest is integrally formed. A pad or cushion 148 may be provided on the arm rest 146 for comfort. The stem 144, in the configuration illustrated, defines a sleeve which fits over the base 136 for vertical movement. The arm rest 146 is lockable in any of a number of discrete vertical positions relative to the seat surface 54 by spring biased movement of the button 140 into an appropriate aligned opening 142. Another ergonomically adjustable feature is thus provided by the arm rest assembly or assemblies.

Exemplary dimensions of the arm rest assembly components are now provided solely to provide an illustration of the size of that assembly. These exemplary dimensions are not to be considered limiting in any way. The base 136 may be 8.5″ in height, 3″ wide at its base, and 2.5″ wide at its upper end. The stem 144 may be 2.75″ in width, and the series of openings 142 may provide for 8″ of adjustability. The pad or cushion may have a 1″ thickness and a 8″ length.

FIGS. 12 and 13 show an ALCAT chair configuration with a substantially rigid, non-collapsible central portion 160. In this configuration, the seat back 72 is identical to the seat back 72 described in connection with the first ALCAT embodiment. Leg extensions 154 of this configuration, however, differ from the leg extensions 104 and 120 of the first ALCAT embodiment in that the extensions 154 of the present configuration are independent of one another and are not interconnected by support struts. In all other respects, the extensions 154 are configured identically to the leg extensions 106 and 120 describe previously.

The non-collapsible central portion 160 of the configuration illustrated in FIGS. 12 and 13 includes a rear support frame 162 and a front support frame 164. Each of the front and rear support frames 162, 164 may be constructed of tubing similar to that of the first support frame 30 or the second support frame 40 of the first ALCAT chair configuration. The rear support frame 162 is composed of a pair of parallel frame elements, each including sections 163 a and 163 b, and a rear cross strut 170. Each frame element is bent slightly in an approximately central portion thereof so that central axes of the sections 163 a and 163 b define an obtuse angle a relative to one another.

The front support frame 164 includes a pair of parallel frame elements, each including sections 165 a and 165 b. In this embodiment, therefore, the tops of sections 163 a define a pair of seat back mounting sections, the bottoms of leg sections 163 b define a pair of rear leg mounting sections, and the bottoms of leg sections 165 b define a pair of front leg mounting sections. The seat section 165 a of each frame element is joined by a weld 166 to one of the rear frame elements at an apex defined by the junction of the sections 163 a and 163 b. The welds 166 also serve to connect the rear cross strut 170 between the apices of the rear frame elements. The front support frame 164 also includes a front cross strut 172. Each of the front support frame elements is bent significantly in an approximately central portion thereof so that central axes of the sections 165 a and 165 b define a small obtuse angle μ (less than approximately 120°) relative to one another, thus eliminating any need to weld the sections 165 a and 165 b together. Each seat section 165 a of the front support frame 164 is joined by another weld 166 to one end of a front cross strut 172, while each leg section 165 b receives one of the extensions 154 as shown. A seat 180, defining a seat surface, is removably mounted on the seat sections 165 a and/or the cross struts 170, 172 as illustrated.

FIG. 14 illustrates a “base” position of a user that allows freedom of movement and natural return to a “base” or “norm,” and is considered the most relaxed sitting position. The base position shown in FIG. 14 minimizes the pull of gravity on the body and associated stresses produced due to misalignment. This is due to the essentially upright or perpendicular position of the user's torso relative to the seat surface, which minimizes the body area subjected to the force of gravity. The user's position shown in FIG. 14 is suitable for times in which the ischia (sit bones) of the user are located at or near the edge of the seat surface. When viewed laterally, with “good” sitting posture, a plumb line P perpendicular to the floor F is aligned with the user's ear, shoulder, hip joint, and ischium. In the preferred, most comfortable sitting position, a line L parallel to the floor at the level of the user's hip joint is slightly higher than the user's knee joint. Many professionals who spend a great deal of time sitting, such as musicians, prefer the position shown in FIG. 14, as that position allows the entire pelvic area to be aligned in a manner similar to the alignment provided by way of proper standing posture. As the knees of the user are lifted, muscles in the lumbar sacral area are put in tension.

The position illustrated in FIG. 15 is similar to that illustrated in FIG. 14, but with buttocks of the user positioned so as to protrude partially through an open space surrounded, for example, by the cushion 82, the seat surface 54, and the side legs 32 of the first ALCAT chair configuration. The open space should be sufficiently wide and tall to permit the buttocks to readily protrude as illustrated. As FIG. 15 shows, the plumb line P can be maintained with provision of an open space having adequate area. The adjustable leg extension frames or leg extensions and the adjustable back rest of the ALCAT chair allow vertical adjustment of portions of the seat surface so that the knee of a user is at or below the level of the hip joint. Each individual user, of course, could modify the positions of the back rest cushion and either the adjustable leg extension frames (FIGS. 1-2, 4, and 8-10) or any of the individual legs (FIGS. 12 -13) for optimal comfort. The ALCAT chair configuration thus facilitates good, relaxed posture and, at the same time, provides adequate total back support when a user is in a proper sitting position so as to produce greater comfort for prolonged sitting sessions, thus rendering it ideal for musicians or other individuals who find it necessary or desirable to remain seated for extended time periods.

The foregoing disclosure has been set forth merely to illustrate the invention and is not intended to be limiting. Since modifications to the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons of ordinary skill in the art, the invention should be construed to include everything within the scope of the appended claims and equivalents thereof. 

1. A chair adapted to provide comfort during prolonged seating periods and facilitating proper sitting posture comprising: a central chair portion defining a pair of seat back mounting sections, a pair of front leg mounting sections, a pair of rear leg mounting sections, and a seat surface; a seat back including a pair of seat back extensions, each of the seat back extensions mountable on one of the seat back mounting sections; a pair of front leg extensions mountable on the front leg mounting sections of the central chair portion; and a pair of rear leg extensions mountable on the rear leg mounting sections of the central chair portion; wherein the seat back, the front leg extensions, and the rear leg extensions are all adjustable relative to the seat surface and lockable in any of a plurality of discrete positions with respect to the seat surface.
 2. The chair of claim 1, wherein the central chair portion is collapsible.
 3. The chair of claim 1, further comprising manually operable locking devices adapted to releasably secure the seat back, the front leg extensions, and the rear leg extensions in position relative to the seat surface.
 4. The chair of claim 3, wherein at least one of the locking devices is formed by a manually releasable latch, disposed on the central chair portion, that is biased into locking engagement.
 5. The chair of claim 2, wherein the pair of front leg extensions are substantially rigidly connected to each other.
 6. The chair of claim 5, wherein the front leg extensions are interconnected by a support strut.
 7. The chair of claim 2, wherein the pair of rear leg extensions are substantially rigidly connected to each other.
 8. The chair of claim 7, wherein the rear leg extensions are interconnected by a support strut.
 9. The chair of claim 1, further comprising at least one arm rest assembly having an arm rest surface also lockable in a plurality of discreet positions relative to the seat surface.
 10. The chair of claim 9, further comprising a manually operable locking device adapted to releasably secure the arm rest surface in position relative to the seat surface.
 11. The chair of claim 10, wherein the locking device is formed by a manually releasable latch, disposed on the central chair portion, that is biased into locking engagement.
 12. The chair of claim 11, wherein the locking device includes a base affixed to a side of a seat frame supporting the seat surface.
 13. The chair of claim 1, wherein the central chair portion is substantially rigid and non-collapsible.
 14. The chair of claim 1, further comprising rollers or casters disposed at ends of the front and rear leg extensions.
 15. The chair of claim 5, wherein the pair of rear leg extensions are also substantially rigidly connected to each other.
 16. A process facilitating proper seating to provide comfort during extended periods of sitting comprising: providing a central chair portion including a pair of seat back mounting sections, a pair of front leg mounting sections, a pair of rear leg mounting sections, and a seat surface; mounting a seat back including a pair of seat back extensions on the seat back mounting sections such that each of the seat back extensions is received on one of the seat back mounting sections; mounting a pair of front leg extensions on the front leg mounting sections of the central chair portion; mounting a pair of rear leg extensions on the rear leg mounting sections of the central chair portion; and adjusting at least one of the seat back, the front leg extensions, and the rear leg extensions relative to the seat surface and locking it in any of a plurality of discrete positions with respect to the seat surface.
 17. The process of claim 16, wherein the central chair portion is collapsible.
 18. The process of claim 16, wherein the at least one of the seat back, the front leg extensions, and the rear leg extensions is releasable from the discrete positions by operating a manually operable locking device.
 19. The process of claim 18, wherein at least one of the locking devices is formed by a manually releasable latch, disposed on the central chair portion, that is biased into locking engagement.
 20. The process of claim 16, wherein the central chair portion is substantially rigid and non-collapsible. 